Process for the polymerization or copolymerization of vinyl chloride

ABSTRACT

Polymers and copolymers of vinyl chloride having good heat stability and antistatic properties are prepared by polymerization in aqueous emulsion in presence of emulsifying agents systems comprising ammonium salts of fatty acids and alkaline alkyl sulphonates or alkyl aryl sulphonates. The latter is gradually introduced during polymerization while the first is present at the beginning of reaction. The ammonium salts are converted into metal salts at the end of polymerization.

United States Patent 1 Mathieu [451 July 15, 1975 1 PROCESS FOR THEPOLYMERIZATION OR COPOLYMERIZATION OF VINYL CHLORIDE [75] Inventor:Alexis Mathieu, Brussels, Belgium [73] Assignee: Solvay & Cie.,Brussels, Belgium 22 Filed: Apr. 4, 1973 [21] Appl. No.: 348,264

[30] Foreign Application Priority Data May 25, 1972 France 72.18808 [52]US. Cl 260/92.8 W; 260/87.1; 260/87.5 C;

260/D1G. 21; 260/D1G. 15 [51] Int. Cl ..C08f1/13;C08f 3/30 [58] Field ofSearch. 260/92.8 W, DlG. 15, DIG. 21

[56] References Cited UNITED STATES PATENTS 2,674,593 4/1954 Condo260/92.8

3,226,350 12/1965 Smiths; 260/29.6

3,311,579 3/1967 Donat 260/23 3,370,028 2/1968 De Wald... 260/233,546,154 12/1970 Hwa 260/29.6 3,546,193 12/1970 Benetta 260/92.8

Primary Examiner-Joseph L. Schofer Assistant Examiner-John KightAttorney, Agent, or FirmSpencer & Kaye [57] ABSTRACT 9 Claims, NoDrawings PROCESS FOR THE POLYMERIZATION OR COPOLYMERIZATION OF VINYLCHLORIDE The present invention relates to a process for thepolymerisation or copolymerisation of vinyl chloride in aqueousemulsion.

It is common practice to use the technique of polymerisation in aqueousemulsion for the preparation of vinyl chloride polymers In this processthe monomer or monomers is or are polymerised in an aqueous medium inthe presence of emulsifying agents and with the help of water-solublecatalysts.

Many compounds have already been used as emulsifying agents.

Of these compounds alkaline alkyl sulphonates and alkyl aryl sulphonateswith a long alkyl chain on the one hand and ammonium salts of long chainfatty acids on the other hand are widely used in industry.

The properties of the polymer latices and the polymer itself varydepending on the nature of the emulsifying agent.

Thus the use of alkaline alkyl sulphonates or alkyl aryl sulphonatesresults in polymers which, when solid, take the form of an anti-staticpowder with good wettability. These properties are an advantage forcertain applications and particularly the production of batteryseparators and end-products having good anti-static characteristics.

As against this the polymer in the body of the latex is in the form ofvery small elementary particles of well below 0.03 microns in diameter.The disadvantage of this is that agglomerates readily form within thebody of the latex. These agglomerates have to be separated from thepolymer, thereby reducing the yield. Furthermore it is obvious that thesmaller the polymer particles the more difficult it will be to separatethe particles from the aqueous medium by conventional methods such asspray drying. If the emulsifying agents remain in the solid polymer theywill impart poor heat stability.

The use of ammonium salts of fatty acids as emulsifying agents produceslatices in which the polymer is in the form of larger elementaryparticles, usually greater than 0.05 microns. Consequently the laticesare mechanically stable.

The polymer can then be readily separated from the aqueous phase byspray drying.

Finally ammonium salts of fatty acids have a further advantage that isby no means negligible. Before the polymer is separated from the aqueousphase they can in fact be converted by neutralisation into metal soapswhich are preferably alkaline and are excellent heat stabilisers for thepolymer.

However, polymers prepared with ammonium salts of fatty acids asemulsifying agents also possess disadvantages for certain applications.In particular the polymer does not exhibit good wettability and is notsufficiently anti-static.

In accordance with the present invention, a process has been developedfor the polymerisation or copolymerisation of vinyl chloride in aqueousemulsion which employs both ammonium salts of fatty acids and alkalinealkyl sulphonates or alkyl aryl sulphonates as emulsifying agents. Theuse of these two types of compound under certain conditions makes itpossible to combine their advantages while avoiding their disadvantages.

The present invention relates to a process for the polymerisation orcopolymerisation of vinyl chloride in aqueous emulsion, chacterised inthat polymerisation is started in the presence of 0.l to 1.5% by weight,calculated on the monomer charge, of an emulsifying agent selected fromthe group comprising ammonium salts of long chain fatty acids andmixtures thereof. 0.3 to 2% by weight, calculated on the monomer charge.of an emulsifying agent selected from the group comprising alkalinealkyl sulphonates, alkaline alkyl aryl sulphonates and mixtures thereofis gradually introduced during polymerisation and the ammonium salts areconverted into metal salts at the end of polymerisation.

The ammonium salts used as emulsifying agents from the start ofpolymerisation are preferably derived from I saturated fatty acids whosechain contains from 10 to 18 carbon atoms. Examples of these include inparticular salts of lauric, myristic, palmitic and stearic acid.

The proportion of ammonium salts employed is unimportant as far as theparticle size of the polymer is concerned. From this angle therefore itcan safely be above the critical micelle concentration.

However, this amount is a function of the heat stability that it isdesired to impart to the polymer by the conversion of the ammonium saltinto a metal salt and preferably a sodium soap after polymerisation andbefore the aqueous phase is separated off. As little as 0.1% by weightcalculated on the monomers is sufficient for the first signs ofstabilisation to appear. Beyond l.5% by weight the increase in heatstability is negligible and the polymer then exhibits the disadvantageof insufficient purity. Generally speaking it is preferable to use 0.3to 1% by weight of ammonium salts of fatty acids.

The alkaline alkyl sulphonates or alkyl aryl sulphonates introducedlater preferably possess a long alkyl chain containing from 10 to 18carbon atoms and preferably 12 to 16 carbon atoms.

The amount of these compounds to be used is a function of theanti-static properties the polymer is required to possess. It has beenfound that at least 0.3% by weight calculated on the monomers isrequired for an anti-static effect to appear. Beyond 2% by weight themarginal increase in anti-static properties becomes negligible and doesnot compensate for the increasing loss of heat stability. The bestresults are obtained by using 0.5 to 1.5% by weight of alkaline,preferably sodium, alkyl sulphonate or alkyl aryl sulphonate.

The introduction of the alkaline alkyl sulphonates or alkyl arylsulphonates into the reaction medium starts when the particle size hasbeen established, in other words preferably after conversion has reached5 to 25% and preferably about 10%. Introduction may be continued untilpolymerisation ends or until at least 50% and preferably less thanconversion has been reached. The rate of introduction is not criticaland is generally constant.

To avoid instability of the reaction medium due to inadequate protectionof the particles provision should preferably be made for all thealkaline alkyl sulphonate or alkyl aryl sulphonate to be introducedbefore conversion reaches about 80%.

After polymerisation ceases but before the polymer is separated from theaqueous medium the ammonium salt of the fatty acid is converted into analkaline salt. This conversion, which is preferably carried outimmediately after the unreacted vinyl chloride has been vented and forexample after the latex has been cooled to room temperature, is effectedby the addition of a basic compound of an alkali metal in aqueoussolution, preferably a hydroxide and in particular sodium hydroxide. Theamount of basic compound used depends then introduced in the form of anaqueous solution.

The autoclave was closed and 1.000 g of vinyl chloride were introduced.The medium was heated to 50C.

The moment polymerisation started was regarded as on the amount ofammonium salt present and is prefcr- 5 being the time I v.; ably between0.01 and 0.3% by weight calculated on From t 30 minutes to r,,+ 3 hours30 minutes (exthe monomers. cept in Examples 1 to 3) sodium alkylsulphonate or so- Having now described the particular conditions thatdium alkyl aryl sulphonate was introduced continucharacterise thepolymerisation process forming the ously and at a constant rate in theform of a concenobject of the present invention it should be noted thattrated aqueous solution in amounts that varied with the the otherpolymerisation conditions are the classic coneXamplesditions used in thepolymerisation of vinyl chloride in When the pressure inthe autoclavehad fallen by 5 aqueous emulsion which are well known to persons kg/cmthe residual vinyl chloride wasvented and the skilled in the art. Hencethe working temperature is latex was cooled. Caustic soda was then addedin the generally between 40 and 70C and the catalyst is a form of adilute solution and in amounts varying with water-soluble free radicalcatalyst. Examples include the amount of the ammonium salt of a fattyacid that hydrogen peroxide, alkaline and ammonium persulhad beenemployed. phates, Redox systems etc. Conversion was about 95% in all theexamples.

The process forming the object of the present inven- The variousevaluation tests were then carried out. tion can be used for thehomopolymerisation of vinyl The proportion of lumps or agglomeratesformed chloride and its copolymerisation with up to 20% by i gpolymerisation was determined by filtering weight of a copolymerisableethylenically unsaturated gh a 250 micron Sieve- The amount of P Ycomonomer such as vinyl acetate, propylene, ethylene, retained on theSieve i an ldea of the m Yleld i at Th that had resulted. sobutene c. eprocess offers a number of particu I larly important advantages. ltresults in mechanically The dlametcr of the elFmemary y f PamcleS instable latices that can be readily spray dried. It makes the latex fassessed electliofl mlcroscopeit possible to avoid the formation ofagglomerates dur- T0 determme mechalllcal stablmy 9 the latex l ingpolymerisation that would be detrimental to the was introduced into acylindrical container where it yield. The solid polymers exhibit greatheat stability was agltated by means 9 a loomed dlsc ro ta nng at hlghafter separation from the aqueous phase and can there- The h m sedcondsl d for the fore be shaped under severe conditions while still givt iCoagu ateiwas gg' d h 1 ing end-products with little discolouration.Furthert f out f S l t e atex more the end-products possess goodanti-static charac- 15 0 6 sa 6 y e 0 Spray rymg' The heat stability ofthe polymer was measured as teristics. The polymers can be used in theproduction,

follows: the polyvinyl chloride powder was placed in a e.g. by powdersintering, of battery separators with O sample holder immersed in an oilbath at 180 C. The minimal discolouration that are readily wetted inelectime that elapsed before hydrogen chloride started to trolytic bathsand therefore offer little resistance to the l d f h h f h f the currentwhich is an important pro ert 8V9 ve pr-Ovi e a measure 0 t e eat-StaHty o t e P if O f p y 40 resin. This time was measured by carrying overthe hyype 0 drogen chloride in nitrogen and absorbing it in water Anumber of dfferem polyvmyl chlondes were whose conductivity increasedwhen the hydrogen chlopared t t thedadvamtahges gl t gi the rideappeared. The stability of the polymer was charac- Presen l were en 6 Ovanous terised by the time required for this increase in conductests toconfirm their properties. tivity to become apparent Examples 1 to 3 areIncluded for Purposes of Compar The time must exceed about 4 minutes andpreferazll fi d d h f n bly about 8 minutes for the resin to exhibitsatisfactory e po ymers were prepare un er t e o owing Stabilitycomgiionszfd d 0 5 f I To assess the anti-static properties of the resinthe 0 g 0 lstl 8 Water g 0 ammonium Persu polymer was pressed into asheet which was placed in Pi anddan f g s Salli of a fatty t f l g anelectrical field at 8 kilovolts. The times required for I at Varie Wlt Ie eXamp 65 p of p e charging and discharging the sample were measured.where the only emulsifying agent was sodium alkyl sul- Th polymer hibi dtit i tie if phonate) were introduced at room temperature into a thesetimes are l h about 3 i t 4 litre autoclave provided with a stirrer anda thermo- Th ifi di i l d i h of th statically controlled jacket. Thewhole was blanketed amples a d the lt of th ev l ati tests are comwithnitrogen to remove oxygen. 1 g of ammonia was bined in the followingtable:

TABLE Poly- Agglo- Mechmerimerates ani- Exam- Nature and Nature andCaustic sation during Elementary cal Heat Anti-static plcs amount ofamount of soda time Poly particles stahstability properties emulsifyingemulsifying introduced meriility of the Dishargagent agent at the endsation of the polymer ing Chargintroduccd at introduced of the testlatex time ing the start of later time polymerisation g/kg g/kg monomerg/kg monomer g/kg monomer h.min monomer microns sec min min min Iammonium 5.00 30 005-0. l 5 20 '4 I 20 m y ristate 9 TABLE ContinuedPoly- Agglo- Mechmerimerates ani- Exam- Nature and Nature and Causticsation during Elementary cal Heat Anti-static ples amount of amount ofsoda time Polyparticles stabstability properties emulsifying emulsifyingintroduced meriility of the Dishargagent agent at the end sation of thepolymer ing Chargintroduced at introduced of the test latex time ing thestart of later time polymerisation g/kg g/kg monomer g/kg monomer g/kgmonomer h.min monomer microns see min min min 2 ammonium 1.5 5.00 300.05-0. l 5 120 30 120 120 myristate ll 3 sodium 3.00 30 0.03 5 3 0.50.5

alkyl sulphonate l l 4 ammonium sodium alkyl 1 4.45 20 005-018 200 20 33 myristate 6 sulphonate 3 5 ammonium sodium alkyl 0.5 4.30 15 0.05-02500 7 2 3 myristate 3 sulphonate 6 6 ammonium sodium alkyl 0.5 4.15 130.05-0.2 600 5 0.5 0.5

myristate 3 sulphonate l 7 ammonium sodium alkyl 0.4 4.45 13 005-022 6004 0.5 0.5

stearatc 3 sulphonate l0 8 ammonium sodium alkyl 0.4 5.15 12 0.06-0.23600 4 l 0.6

stearate 3 aryl sulphonate l0 9 ammonium sodium alkyl 1.35 4.30 10005-015 600 11 0.5 0.5

stearate l0 sulphonate l0 10 ammonium sodium alkyl 2 4.15 10 005-012 60012 0.6 l

stcarate l sulphonate l 1 ammonium sodium alkyl 1.35 4.15 8 005-015 60010 0 0 stearate l0 sulphonate l5 12 ammonium sodium alkyl 1.35 4.15 80.05-0.15 600 6 0 0 stearate l0 sulphonate 1 claim: tion of 0.5 to 1.5%by weight calculated on the monol. Process for the polymerisation ofvinyl chloride in aqueous emulsion. comprising:

starting the polymerisation in the presence of 0.1 to

1.5% by weight. calculated on the monomer charge, of an emulsifyingagent selected from the group comprising the ammonium salts of longchain saturated fatty acids having 10 to 18 carbon atoms, and mixturesthereof.

gradually introducing during polymerisation, when conversion has reached5%. 0.3 to 2% by weight, calculated on the monomer charge, of anemulsifying agent selected from the group comprising alkaline alkylsulphonates having 10 to 18 carbon atoms in the alkyl chain. alkalinealkyl aryl sulphonates having 10 to 18 carbon atoms in its alkyl chain.and mixtures thereof. and

converting the ammonium salts into alkaline metal salts at the end ofpolymerisation.

2. Process for the polymerisation or copolymerisation of vinyl chloridein aqueous emulsion in accordance with claim 1, wherein the ammoniumsalt of a fatty acid is used in the proportion of 0.3 to 1% by weightcalculated on the monomer charge.

3. Process for the polymerisation or copolymerisation of vinyl chloridein aqueous emulsion in accordance with claim 1, wherein the ammoniumsalt is derived from saturated fatty acids.

4. Process for the polymerisation or copolymerisation of vinyl chloridein aqueous emulsion in accordance with claim 1, wherein the emulsifyingagent introduced during polymerisation is used in the propormer charge.

5. Process for the polymerisation or copolymerisation of vinyl chloridein aqueous emulsion in accordance with claim 1, wherein the alkyl chainof the alkaline alkyl sulphonates and alkaline alkyl aryl is from 12 to16 carbon atoms.

6. Process for the polymerisation or copolymerisation of vinyl chloridein aqueous emulsion in accordance with claim 1, wherein the alkalinesulphonate is continuously introduced into the polymerisation medium assoon as conversion has reached a value exceeding about 10% and until ithas reached a value exceeding about 50%.

7. Process for the polymerisation or copolymerisation of vinyl chloridein aqueous emulsion in accordance with claim 1, wherein the ammoniumsalt is converted into an alkaline salt at the end of polymerisation bythe addition of a basic compound of an alkali metal in the proportion of0.01 to 0.3% by weight calculated on the monomer mixture.

8. Process for the polymerisation or copolymerisation of vinyl chloridein aqueous emulsion in accordance with claim 1, wherein the alkalinesulphonate is used in the proportion of 1.0 to 2.0% by weight calculatedon the monomer charge.

9. Process for the polymerisation of vinyl chloride in aqueous emulsionin accordance with claim 1, wherein all of the sulphonate emulsifyingagent is introduced before conversion reaches

1. PROCESS FOR THE POLYMERISATION OF VINYL CHLORIDE IN AQUEOUS EMULSION,COMPRISING: STARTING THE POLYMERISATION IN THE PRESENCE OF 0.1 TO 1.5%BY WEIGHT, CALCULATED ON THE MONOMER CHARGE, OF AN EMULSIFYING AGENTSELECTED FROM THE GROUP COMPRISING THE AMMONIUM SALTS OF LONG CHAINSATURATED FATTY ACIDS HAVING 10 TO 18 CARBON ATOMS, AND MITURES THEREOF,GRADUALLY INTRODUCING DURING POLYMERISATION, WHEN CONVERSION HAS REACHED5%, 0.3 TO 2% BY WEIGHT, CALCULATED ON THE MONOMER CHARGE, OF ANEMULSIFYING AGENT SELECTED FROM THHE GROUP COMPRISING ALKALINE ALKYLSULPHONATES HAVING 10 TO 18 CARBON ATOMS IN THE ALKYL CHAIN, ALKALINEALKYL ARYL SULPHONATES HAVING 10 TO 18 CARBON ATOMS IN ITS ALKYL CHAIN,AND MIXTURES THEREOF, AND CONVERTING THE AMMONIUM SALTS INTO ALKALINEMETAL SALTS AT THE END OF POLYMERISATION.
 2. Process for thepolymerisation or copolymerisation of vinyl chloride in aqueous emulsionin accordance with claim 1, wherein the ammonium salt of a fatty acid isused in the proportion of 0.3 to 1% by weight calculated on the monomercharge.
 3. Process for the polymerisation or copolymerisation of vinylchloride in aqueous emulsion in accordance with claim 1, wherein theammonium salt is derived from saturated fatty acids.
 4. Process for thepolymerisation or copolymerisation of vinyl chloride in aqueous emulsionin accordance with claim 1, wherein the emulsifying agent introducedduring polymerisation is used in the proportion of 0.5 to 1.5% by weightcalculated on the monomer charge.
 5. Process for the polymerisation orcopolymerisation of vinyl chloride in aqueous emulsion in accordancewith claim 1, wherein the alkyl chain of the alkaline alkyl sulphonatesand alkaline alkyl aryl is from 12 to 16 carbon atoms.
 6. Process forthe polymerisation or copolymerisation of vinyl chloride in aqueousemulsion in accordance with claim 1, wherein the alkaline sulphonate iscontinuously introduced into the polymerisation medium as soon asconversion has reached a value exceeding about 10% and until it hasreached a value exceeding about 50%.
 7. Process for the polymerisationor copolymerisation of vinyl chloride in aqueous emulsion in accordancewith claim 1, wherein the ammonium salt is converted into an alkalinesalt at the end of polymerisation by the addition of a basic compound ofan alkali metal in the proportion of 0.01 to 0.3% by weight calculatedon the monomer mixture.
 8. Process for the polymerisation orcopolymerisation of vinyl chloride in aqueous emulsion in accordancewith claim 1, wherein the alkaline sulphonate is used in the proportionof 1.0 to 2.0% by weight calculated on the monomer charge.
 9. Processfor the polymerisation of vinyl chloride in aqueous emulsion inaccordance with claim 1, wherein all of the sulphonate emulsifying agentis introduced before conversion reaches 80%.